Re: SSTC Magnifiers / High Frequency - High Voltagetransformers

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "David Sharpe by way of Terry Fritz <twftesla-at-qwest-dot-net>" <sccr4us-at-erols-dot-com>

Dan

Tesla list wrote:

 > Original poster: "Mccauley, Daniel H by way of Terry Fritz 
<twftesla-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>
 >
 > <SNIPP>

 > Actually, it is not as difficult as it seems.  Soft ferrite cores
 > are readily available in a variety of
 > sizes from various manufacturers including ferroxcube, fair-rite, etc...
 > With a large core, voltage stand-off isn't really a problem.  Basically
 > U-Cores work extremely well and with using
 > a ferrite such as 3C90, 3C91, etc..., efficiency and operation at high
 > frequencies (100-300kHz) is good.
 > For higher powers, cooling is required as the cores can get fairly hot.

 > ------------------------------------

1.  What core # and bobbin assembly are you using?
2.  Where to buy (or get "Engineering Samples"  :^)  )?
3.  One way to build a HV driver would be place primary
      on one leg of core and use "segmented" scramble wound
      secondary.  This is HV design used on electronic NST's.
------------------------------------

 >
 > My current design utilizes a Ferrox U-Core using 3C91 ferrite core with
 > primary at 30 turns, and secondary at 150 turns
 > for a 1:5 step-up transformer design.

 > ---------------------------------------

For Bylund's final bridge design, he was running +/-160VDC bus
and was getting about 20kV (pk-pk) out if memory is not failing me...
Was pushing 1:16 turns ratio; corona, insulation failure was a
major problem.  I believe in final imbodiment, he had to use
an oil immersed driver transformer to control dielectric breakdown.

Unit could get up to 18" discharges.  Used bipolar transistors with
proportional drive (with Baker clamps) -at- 100kHz.  Worked remarkably
well considering the "sucky" HV transistors that were available.  I actually
designed (but never built) a half bridge FET unit about same time,
thought it would have been simple, it would have detonated many FET's.
I thought FET body diode would have been "good enough", had
no schottky + HV flyback diodes in the circuit.  Was going to used
a SG3526 and Pulse Engineering GDT.
-------------------------------------

 > Dan

Regards
Dave Sharpe, TCBOR
Chesterfield, VA. USA